A good rule of thumb is that 1 centimetre of melted snow equals 1 millimetre of water. Thus, 10 millimetres of rain would correspond to a snowfall of 10 centimetres. In reality, there is some variation depending on the type of snow, but in practice this rule holds with sufficient accuracy.
Day-to-day weather forecasts differ from climate change forecasts that extend over decades. Climate research investigates the long-term averages of atmospheric features and their slow changes. The factors affecting atmospheric features differ from the factors affecting the daily weather. For example, climate forecasts take account of greenhouse gas concentrations, which increase year by year and affect the temperature of the whole atmosphere, thereby slowly altering the climatic conditions of large regions.
Climate change is reflected in Finland’s temperatures, too. Since the 1960s, the annual mean temperature in Finland has risen on average by 0.3 degrees per decade. Owing to human activity, the global climate is constantly becoming warmer, but the intensity and impacts of the change vary from region to region. In Finland and other northern regions, temperatures rise more rapidly than the global average. The rate of warming in the Arctic regions is about double the global average. In Finnish Lapland and northern parts of Fennoscandia, the 1930s were exceptionally warm; in those areas, temperatures are therefore just passing the old records.
In Finland, winter temperatures are rising on average more than summer temperatures. For instance in Helsinki, the year 2008 broke all previous temperature records. However, the record-high mean temperature is explained by the exceptionally warm and mild winter. Especially in southern and central parts of the country, mild winters will be more frequent. Since there will be less snow, winters will also be darker. Summers will become warmer, too, but this effect will be seen and felt more slowly than the warming of winters.
The impact of climate change on temperatures is still small when compared against the wide natural variation, but in the coming decades the change will gradually become clearer. However, even though the climate changes, its variability will remain. In other words, some periods will still be colder and some others warmer than average.
The IPCC itself does not conduct new research on climate change; instead, it analyses and compiles existing scientific data. The physical basis of climate change is sound but the impacts of climate change are more difficult to assess. However, individual errors do not invalidate the message of the extensive summary reports: climate change is the most serious challenge facing humankind. Irrespective of the ongoing debate concerning the credibility of the IPCC, climate change is continuing and will have increasingly evident impacts with time. The latest research findings indicate that climate change is progressing more quickly than anticipated. The IPCC intends to develop its working methods further to eliminate all errors in its reports. At present, the IPCC is working on the Fifth Assessment Report, scheduled for publication in 2014. The IPCC is – and will remain – the most reliable information source on climate change.
The climate service has a digital data base, which covers mainly the period from 1961 onwards. In addition the climate service has some long digital data series to cover the earlier years within a considerably coaser station network. All other data exists just in written form.
With the previously mentioned data sources in mind the Finnish Meteorological Institute can prepare a list of for example 100 coldest minimum temperatures (at the height of 2 meters above ground) measured in Finland. The price of this task will depend on, which data sources should be covered, and will be considerably higher in case of a manual scrutiny of written archived data sources.
For more information please contact the Climate Service .